In conventional manner, in the case where a metallic workpiece, for example, is cut, saws such as a circular saw and a band saw have been widely used in the prior art. A saw blade serving as a cutting tool for use in the above-described saw is configured such that numerous cutting teeth for cutting the workpiece are arranged at appropriate pitches. Exemplary types of saw blades include a so-called set tooth type and a dovetail shaped set tooth type.
The above-described set tooth is provided with a straight tooth, as viewed in a cutting direction of the cutting teeth, and left and right set teeth whose tooth tips are set in a lateral direction in order to perform a setting work in the lateral direction. Chattering vibration, noise or the like generated during a cutting work of the workpiece has been coped with by designing an arrangement pattern of the appropriate number of straight teeth and the plurality of left and right set teeth in any one of various kinds of patterns such as a raker set, a wave set and a straight set or arranging the cutting teeth at unequal pitches.
The above-described dovetail shaped set tooth type is not provided with left and right set teeth which are set in the lateral direction, but is provided at each of the cutting teeth with a dovetail shaped chip which is gradually enlarged in the lateral direction on a tooth tip side, wherein the chip may have various shapes and dimensions, as disclosed in, for example, Japanese Patent Application Laid-open Nos. 10-193219 and 2000-317729.
As shown in FIGS. 10A to 10C, a conventional saw blade 101 of the set type includes a blade base 103, which is provided with a straight tooth 105 without setting in a lateral direction, as viewed in a cutting direction of a workpiece W by means of the saw blade 101, and left and right set teeth 107 and 109, which are set in the lateral direction. With the above-described configuration, the thicknesses of the straight tooth 105 and the left and right set teeth 107 and 109 are equal to the thickness of the blade base 103.
If a setting quantity, that is, a scarf width S of the left and right set teeth 107 and 109 is small in the above-described saw blade 101, an inclination angle θ of each of the left and right set teeth 107 and 109 becomes small in a vertical direction. Therefore, if respective outside corners 107C and 109C of the left and right set teeth 107 and 109 are finely abraded in a horizontal direction, a vertical dimension H at the abraded portion becomes relatively larger than an abrasion quantity in the horizontal direction. An inner surface F of a cutting groove formed at the workpiece W is brought into larger contact with the abraded portion at the left or right set tooth 107 or 109.
When the workpiece W is cut by the saw blade 101, the left and right set teeth 107 and 109 are elastically deformed in the lateral direction with the application of partial force in the lateral direction. As described above, when the inner surface F of the cutting groove formed at the workpiece is brought into larger contact with the abraded portion at the left or right set tooth 107 or 109, cutting resistance becomes larger, and further, the partial force in the lateral direction exerted on the left and right set teeth 107 and 109 becomes larger. As a consequence, the saw blade 101 is turned into an unstable state, thereby inducing breakage or bending.
In view of this, if the inclination angle θ of each of the left and right set teeth 107 and 109 is to be increased by making constant the scarf width S, i.e., a cutting margin in cutting the workpiece W, a bending position P, at which the left and right set teeth 107 and 109 are bent in the lateral direction, undesirably approaches the tooth tips. In this case, since a fine portion in the vicinity of the tip of the cutting tooth in the saw blade 101 is deformed in the lateral direction with application of lateral large force, the tip of the cutting tooth is largely deformed, i.e., crushed, thereby raising a problem.
In the meantime, the saw blade of the dovetail shaped set tooth type is not provided with left and right set teeth, which are set in a lateral direction, but it is generally configured such that a chip having a trapezoidal shape (i.e., a dovetail shape) in cross section is joined to a tip of a straight tooth without setting in the lateral direction. Here, if an inclination angle of a side surface of the chip portion is to be increased, the bottom side of the trapezoid becomes longer, thereby providing an undesirable configuration in which the chip becomes larger and cutting resistance becomes larger.
The invention has been accomplished to solve the above-described problems experienced in the prior art. Therefore, an object of the invention is to provide a saw blade in which a vertical dimension can be suppressed to a low level in view of a horizontal abrasion quantity at an outside corner of each of left and right set teeth.